Remove userinit from user builds

/data is supposed to be inaccessible to begin with, and we don't
want the init sequence tampered with for user builds

Change-Id: If3eb5573248956a14ad56516a9871758f4c00989
(cherry picked from commit a9d772166365a27181a7441c10a6c60a2bab7dab)

config/common.mk

@@ -93,9 +93,11 @@ PRODUCT_COPY_FILES += \
     vendor/cm/prebuilt/common/etc/init.d/00banner:system/etc/init.d/00banner \
     vendor/cm/prebuilt/common/bin/sysinit:system/bin/sysinit
 
+ifneq ($(TARGET_BUILD_VARIANT),user)
 # userinit support
 PRODUCT_COPY_FILES += \
     vendor/cm/prebuilt/common/etc/init.d/90userinit:system/etc/init.d/90userinit
+endif
 
 # CM-specific init file
 PRODUCT_COPY_FILES += \